Propelling device and method



March 5, 1963 H. B. FORNEY PROPELLING DEVICE AND METHOD 3 Sheets-Sheet 1Filed Dec. 27, 1955 Q m N MN 3 I... f 4... N I II I H I I I/ I n fl H E3 N w Q E m H N w. 2. II II I l I I fi Q Q Q Q NH QNW. NQ Q Q Jmb u mIii 31m? ffarry B. ?517Z 5/ H [2 L 75 March 5, 1963 H. B. FORNEYPROPELLING DEVICE AND METHOD 3 Sheets-Sheet 2 Filed D80. 2'7, 1955LTLF'E 21277 T Ham" B. $51126 I f 2 7. 5

March 5, 1963 H. B. EORNEY 3,079,755

PROPELLING DEVICE AND METHOD Filed Dec. 27, 1955 3 Sheets-Sheet 3 E i iI :q EN a) 1 Q E i f 1 1 E 1' J $1 E R's firaizfmf v Hafry B. 5f119 w a,%M; w%

il L775 United States Patent 3,b?9,755 Patented Mar. 5, 1%53 free3,tl79,755 PROPELLENG DEVICE AND METHQD Harry it. Forney, Richmond; Va,assiguor to Thompson Rama Wooldridge, Inc, Cleveland, Ohio, a,corporation of Ghio Filed Dec. 27, 1955, Ser. No. 555,485 2 Claims. (Cl.60-3932) This invention relates generally to a propelling device andmethod. and more particularly to a device for generating'a jet of gasesand sustaining decomposition ofa fluid propellant. Specifically, theinvention deals .Witha rocket engine and a process of regenerativelydecomposing amonopropellant;v in engine.

' There are two phases in the operation of a monopropellant rockettheinitiation phase. which is a transient condition of greater or lesserduration, and a steady-state operation phase. constant ignition sourcemustbe provided in order to'initiate combustion in the fresh incomingpropellant. Norma'lly this is provided by a recirculation 'zone in whichpart of the hot decomposition products are fed back to the regionwherein the fresh propellant is being injected.

The mechanism is ordinarily that of a recirculating eddy in the internalfiowprocesses. the amount of heat that can be transferred by thispr'ocess is not sufiicient to maintain the decomposition process,-

and all reaction is quenched. In the present invention this difiicultyis overcome by providing mechanical meansous,'however, refers only tothat period of time requiredto establish the steady-state condition, andthis may vary from a matter of seconds to a matter of minutes, but atsome point the glow plug is normally turned off. The well knownmagnesium igniter acts as a chemically energized glow plug in providinga hot clinker. This clinker remains hot a sufliciently long period tocarry,

the over-all reaction through the initiation phase and into thecontinuous phase. A minimum chamber size exists in which transition tothe steady-state phase never occurs that is, the engines run only overthe lifetime of the hot clinker. Most probably, in such cases, theelectrical glow plug would have to be continuous over the entire run.This situation though occurs only with very small.

chambers. On the other hand, even with operable chambets, is, thoseabove the size that require truly continuous ignition, undesirableamounts of carbon form both with.

the electric glow plug and with the magnesium igniter.

In the past, in devices for generating a jet of gases, such as rocketengines or the like, the fuel or propellant has been heated prior toinjection into the reaction chamber. However, when heating the fuel orpropellant before injection into a reaction chamber, at best onlyevaporation is achieved.

In the present invention, a rocket engine or device for generating a jetof gases includes a housing having a reaction or decomposition chamber.A heat exchanger or regenerator is positioned within the reactionchamber for transferring thermal energy to a propellant introduced intothe chamber. for initially raising the chamber pressure and tempera:ture and the temperature of the heat exchanger to an energy levelsufficient to initiate decomposition of the propellant. Evaporation anddecompsitionofthe propellant the reaction chamber of a; rocket:

In the steady-state operationJphase, a.

In very small chambers,

An igniter is mounted in the casing.

is achieved by placing the heat exchanger within the reaction. chamber;The heat exchanger is arranged to-have the. fresh. propellant flow overone surface and the pro-- pellant products of decomposition flow overanother surface and out an exhaust port. The propellant products. ofdecomposition maintain an energy level within the reaction chambersufiicient to sustain decomposition of the propellant.

Alsoin the. present. invention, the igniter is of such a type whichdischarges a gaseous exhaust or product into the reaction chamber. In.other words, essentially no solid residue is introduced into thereaction chamber by the igniter. the propellant and" operation of thegasgenerating'device in a carbon free manner. The igniter may be apyrotecbnic: type, and preferably of the smokeless variety.

Accordingly, it is an. object. of this invention to provide a device forgenerating a. jet of gases by decomposing a propellant in a reactionchamber.. t

Still another object of this. invention isto provide device'for,generating a jet'of gases including a reaction chamber with meanstherein that is capable of transtaining decomposition of amonopropellant.

A still further object of this invention is to provide a device forgenerating ajet of. gases including a reaction chamber having a heatexchanger therein that is capable of effecting a greater heat. exchangeoperation.

Another object of this invention is inv the. provision of a device forgenerating a jet of gases by decomposing a monopropellant in. a reactionchamber that is capable of sustaining decomposition of themonopropellant without the aid of anoutside constant ignition source.

A still further object of this invention is to provide a device forgenerating a jet of gases by decomposing a propellant in a reactionchamberhaving a heat exchanger therein, wherein an igniter dischargeshot. gases into the reaction chamber for raising, the'chamber pressureand temperature and the regenerator temperature to an energy levelsufiicient to initiate decomposition of the propellant.

Another object of this invention resides in the provision of a devicefor generating a jet of gases by decomposing a monopropellant in areaction chamber having a regenerator therein, wherein a pyrotechnicigniter is provided to discharge hot gases into the reaction chamber forraising the chamber pressure and temperature and the regeneratortemperature to an energy level sufficient to initiate decomposition ofthe propellant.

Another object of this invention is to provide adevice for generating ajet of gases by decomposing, a mono propellant in a reaction chamber,wherein decomposition is initiated by an igniter, and wherein ignitionand operation is in a carbon free manner.

A further object of this invention is in the provision of a rocket motorhaving a heat exchanger forpreheating the propellant wherein the heatexchanger is ener-- gized by the propellant products ofdecomposition.

Other objects, features, and advantages of the illVI1-- tion will beapparent from the following detailed'description, taken in conjunctionwith the accompanying sheets with some parts in elevation andothersbrok'en away for purposes of clarity, of a device for generatingajet of gases embodying the invention;

Therefore, the igniter provides ignition of 3 FIGURE 2 is an enlargedtransverse sectional view, with some parts in elevation, takensubstantially along line 11-11 in FIGURE 1 and looking in the directionof the arrows;

FIGURE 3 is a substantially axial sectional view, with some parts inelevation and other parts broken away for.

purposes of clarity, of a modified form of the invention; FIGURE 4 is asubstantially axial sectional view, with some parts in elevation, andother parts broken for purposes of clarity, illustrating still anotherform of the invention;

FIGURE 5 is an enlarged transverse sectional view, taken substantiallyalong line V-V of FIGURE 4 and looking in the direction of the arrows;

FIGURE 6 is a substantially axial sectional view, with some parts inelevation and others broken away for purposes of clarity, of still adifierent form of the invention; and

FIGURE 7 is a transverse sectional view, taken substantially along lineVllVli in FIGURE 6 and looking in the direction of the arrows.

As shown on the drawings:

The present invention is primarily useful in connection with aircraftand jet propelled vehicles where it may be desired to provide a supplyof energy from a device which occupies a small amount of volumetricspace. Specifically, a jet of gases is generated which may, for example,drive .a turbine for generating electrical or hydraulic power. Energy isextracted from a rocket propellant or the like by decomposing thepropellant in a reaction or decomposition chamber. The pressure of thepropellant gases is converted into kinetic energy by delivering thegases through a nozzle or exhaust orifice.

While any type of propellant may be employed with the present invention,preferably a monopropellant is employed, such as ethylene oxide orhydrazine. In the rocket engine field, a monopropellant may be definedas a single fluid which contains within itself all ingredients necessaryto produce useful energy by means of decom position.

While it may be appreciated that the present invention is most useful inconnection with aircraft and rocket powered vehicles, other uses andpurposes may be apparent to one skilled in the art.

Referring now to FIGURES 1 and 2, an engine or device for generating ajet of gases, generally designated by the numeral 10, includes a housing11 or casing having a reaction or decomposition chamber 12 formedtherein. The housing 11 may be of any form, but in this instance, isformed from a pair of cup shaped members welded together at their openends defining a front end 'wall 11a connected to a rear end wall 1117 bya cylindrical wall He. Thus, a substantially cylindrical air tightreaction chamber 12 is formed therein although the chamber may take anyother suitable form.

Disposed within the reaction chamber 12 is a heat exchanger orregenerator 13 which nominally functions to preheat the fresh propellantinjected into the reaction chamber. The heat exchanger may take anydesirable form which is capable of being disposed in the reactionchamber. However, in this embodiment, the heat exchanger 13 is formedfrom an elongated length of tubing which is helically wound in the formof a coil spring. The tubing may be arranged in other shapes such as bybeing formed in a spiral coil. The coils are generally concentric withthe cylindrical walls of the reaction chamber, and the outer peripheriesare slightly spaced from the chamber walls. One end of the coiled tubingis open at 14 into which the propellant products of decomposition flow.The coil having the open end 14 is angularly cut, as seen most clearlyin FIGURE 2 to provide easy access of the decomposition products intothe heat exchanger. However, the end coil may merely be perforated orthe very end ofthe tubing cut off transversely. In other words, otherforms of openings at this end of the tubing may be employed. The otherend of the tubing carries an axially extending portion 15 from theadjacent coil which is suitably secured to the adjacent end wall 11a bywelding or other equivalent means for communicating the heat exchangerwith an exhaust port 16 in the end wall 11a. The exhaust port isprovided with a nozzle or orifice to convert the pressure of thepropellant gases into kinetic energy.

The housing 11 and the heat exchanger or regenerator may be-constructedof any suitable type of material which will withstand the operatingtemperature in decomposing the propellant. Preferably, the heatexchanger may be formed from copper or stainless steel or other materialwhich also has suitable heat transferring characteristics. A rocketpropellant, such as a monopropellant is in troduced or injected into thereaction chamber 12 through the end wall lit: by a fitting 17.Alternatively, the monopropellant may be introduced through thecylindrical wall lie of the casing by a fitting 18. And, if desired, themonopropeliant maybe introduced into the reaction chamber through bothof the fittings 17 and 18 simultaneously. The end wall 11a and thecylindrical wall are suitably tapped to receive threaded ends of thefittings 17 and 18 in tight sealing relationship. While not shown, it isunderstood that the fittings 17 and 18 will be connected with otherconduits or piping which lead to a propellant tank or reservoir.

Where it may be desired to control the propellant flow into the reactionchamber, a pressure picloup 19 is suitably threaded in a tapped bore inthe housing portion 11c for carrying a signal to control valves or thelike (not shown) which control the flow of propellant through thefitting 17 and 18 and into the reaction chamber 12. Otherwise, thispressure pick-up 19 may be employed for controlling other apparatus orinstrumentation.

The end wall ills of the casing 11 is provided with a tapped bore forreceiving the threaded end of a pyrotechm'c igniter 20 in sealingrelationship therewith. Alternatively, the igniter 20 may be of asolid-propellant type, or other type of igniter which is capable ofintroducing hot gases into the reaction chamber 12. Preferably, thepyrotechnic igniter is of the smokeless type wherein essentially nosolid residue exists in the hot exhaust gases. It is desired that only agaseous product or exhaust be introduced into the reaction chamber bythe igniter 20. A squib 21 or" any suitable type, which may be activatedby a small dry cell battery, is carried on the pyrotechnic igniterhousing for energizing the igniter. of operation of the pyrotechnicigniter may be quite brief, but capable of raising the reaction chamberpressure and temperature and the temperature of the heat exchanger to anenergy level sufiicient to initiate decomposition of a monopropellantinjected into the chamber.

In operation of the engine, the squib 21 is activated by a source ofelectrical energy such as a small dry cell battery. This actionenergizes the pyrotechnic igniter which introduces hot gases into thereaction chamber 12. The chamber pressure and temperature and the heatexchanger temperature is thusly elevated by the hot gas discharge of theigniter to an energy level sufiicient to cause decomposition of amonopropellant. A monopropell'ant such as ethylene oxide or hydrazine isthen injected or introduced into the reaction chamber through thefitting 17 or 18 which readily decomposes due to the energy levelcondition in the chamber. The monopropellant products of decompositionflow through the tubing of the regenerator and are released through theexhaust port 16. The monopropellant products of decomposition, in turn,maintain the chamber pressure and temperature and the heat exchangertemperature at such an energy level as to sustain decomposition of themonopropellant subsequent to the introduction of the hot gases into thereaction chamher by the igniter 29. Thermal energy is transferred fromthe monopropellant products of decomposition to the freshly introducedmonopropellant through the medium of the heat exchanger 13, and by themeans of the heat The duration exchanger achieves evaporation anddecompositionofthe incoming monopropellant. Thus, subsequent to theinitialenergization of the pyrotechnic igniter 20, decomposition offresh monopropellant is-maintained within the reaction chamber 12 by theexistence of the regenerative heat exchanger 13.

The combination of the pyrotechnic igniter and the heat exchangerdisposed within the reaction chamber permits in the case ofmonopropellants ignition and operation in the heat exchanger therebyincreasing the efficiency of the engine. By mounting the heat exchangerwithin the reaction chamber, the efiiciency has not only been greatlyincreased, but the space'requi'rement's have been greatly reduced.

Referring to FIGURE 3, a modified engine or device for generating a jetof gases, generally designated by the numeral 16A, is illustrated whichis generally similarto' the embodiment disclos'ed'in FIGURES 1 a'nd2..

In this embodiment, a larger size regenerator or heat exchanger 22 issupported within the reaction chamber 12. This heat exchanger is alsoformed from a length of tubing which is spirally or helically wound, butin this embodiment, the outer peripheries of the coils are sized toengage the cylindrical walls of the reaction chamber.

One other diif-erence lies in the elimination of one of the propellantinlets to the reaction chamber, wherein this embodiment, only thefitting 17 in the'end wall 11a is'provided for introducing thepropellant into the chamber. It is not necessary that two propellantinlets be provided for introducing the propellant into the reactionchamber 12. Moreover, the fact that the coils of the regenerator engagethe cylindrical walls of'thereaction chamber has no effect on theoperation of the engine, although this arrangement provides for easiersupporting of the heat exchanger Within the reaction chamber; Theoperation of this embodiment is substantially identical as the operationof the embodiment in FIGURES l and 2, and therefore will not be set outin detail.

A still diiterent embodiment, shown in FIGURES 4 and 5, is provided witha still different shaped heat exchanger. In this embodiment, the engineor gas generating device 103 includes the housing 11 formedfrorn a pairof cup shaped members to define the reaction chamber 12 similar to thefirst embodiments. The housing 11 is again provided with end walls 11aand 11b and a cylindrical connecting wall 110, and defines asubstantially cylindrically shaped reaction chamber within the housing.

In this embodiment, the regenerator or heat exchanger "3 is in the shapeof a can or hollow cylinder having an open and a closed end. The heatexchanger includes a cylindrical wall 23a which defines with thecylindrical walls of the reacton chamber an annular passageway, and anend wall 23b in slightly spaced relationship from the housing end wall11!) to define a disk-shaped collecting chamber. To support the heatexchanger 23 within the reaction chamber, a plurality of annularlyarranged supporting members 24 are connected at one end to the end wall23b of the heat exchanger and at the other end to the end wall 11b ofthe housing. These supporting members further serve to assure thespacing between the housing end wall and the heat exchanger end wall.While the heat exchanger cylindrical wall 23a appears to be spaced at aconsiderable distance from the inner cylindrical wall of the reactionchamber, it may be appreciated that this distance can be quite small andthat the heat exchanger 23 may be more or less supported on thecylindrical walls of the reaction chamber. It is only necessary thatsufficient space he provided between the regenerator heatexchanger issomewhat different.

pyrotechnic igniter 20 is energized to introduce through 6-, andreaction-chamber wall to allow flow of gases there between.

In-this embodiment, the propellant or monopropellant is again introducedinto the reaction chamber through theend wall 111: and the fitting 17.However, the pyrotechnic igniter 20 is connected to the end wall 11a byan elbow fitting 25 for introducing the hot gases into the reactionchamber and open end of the regenerator 23.

Another difference over the other embodiments lies in the positioning ofthe exhaust port 16, which now is formed in substantially the center ofthe opposite end wall 11b.

The principle of operation of the engine lilb is identical with that ofthe other embodiments, even though the arrangement ofthe components andthe shape of the In'operation, the

the elbow 25 a blast of hot gases into the reaction chamber 12. and theopen end of the heat exchanger 23; This action elevates the reactionchamber pressure and temperature and the heat exchanger temperature toan energy level sufficient to initiate decomposition of a monopropellantwhich. is then injected or introduced into the reaction. chamber throughthe fitting 17. The monopropellant hits the inside of the heat exchangerand wall 23b and splat- 1 ters in all directions before-taking a pathtoward the open end of the heat exchanger and adjacent the inner surfaceof the heat exchanger. cylindrical wall 23a. Due to the energy levelconditions set up by the pyrotechnic igniter 20, the monopr'opellantbegins to decompose; and the products of decomposition flow'around theopen end of the heat exchanger and back along the annular passagewaydefined by the cylindrical walls of the reaction cham her and the outercylindrical surface of the heat exchanger cylindrical wall 230'. As theproducts of decomposition flow towards the end wall 11b of the housing,thermal energy is imparted to the heat exchanger 23 and, in turn,transferred to the fresh monopropellant. The products of decompositionthen collect in the disk-shaped chamber defined by the housing end wall11b and the heat exchanger end wall 23b and are released through theexhaust port 16; Thus, thermal energy is transferred from the productsof decomposition through the heat exchanger cylindri'calwall 23a and theend wall 23b to the incoming fresh monopropellant introduced into thereaction chambet and the open end of'the heat exchanger 23. And, as inthe other embodiments, the products of decomposition maintain the energylevel within the reaction chamber at a point sufiicient to maintaindecomposition of the monopropellant after the pyrotechnic igniter hasbeen deenergized.

A still different form of the invention is illustrated in FIGURES 6 and7, wherein an engine or gas generating device 10C includes the same typeof housing 11 as set forth in the other embodiments.

In this embodiment, a regenerator or heat exchanger 26 is againpositioned within the reaction chamber 12, and the heat exchanger is inthe form of an elongated accordion pleated member. This member is hollowand open at the end adjacent the housing end wall 11a, and closed at theother-end by an end wall 26a near the other housing end wall 11b. Theinterior of the heat exchanger intercommu'nicates'with the exhaust port16 disclosed in the housing end wall 11]; through a connecting tube 26bthat is connected at one end to an aperture in the heat exchanger endwall 26a and at the other end to the inner surface of the housing endwall 11b in registry with the exhaust port 16.

The monopropellant is introduced into the reaction chamber through thehousing end wall 11b and the fitting 17 mounted therein. It may be notedthat the inlet is substantially centrally located in the end wall 11b,while the exhaust port 16 is positioned radially outwardly from themonopropellant inlet. Introduction of the hot gases from the pyrotechnicigniter is also through the end wall 11b which mounts the igniter.

' Again, the general principle of operation of the gas generating deviceltic is, in Connection with the decomposition of the monopropellant inthe reaction chamber 12, substantially identical as the operation of theengines 16, A and 16B. Initially, the pyrotechnic igniter 20 isenergized which introduces into the reaction chamber 12 through thehousing end wall 1112 a stream of hot gases that raise the reactionchamber pressure and temperaiure and the heat exchanger temperature toan energy level sufiicient to initiate decomposition of amonopropellant. The incoming monopropellant, being introduced throughthe housing end wall 11b flows over the outer surfaces of the heatexchanger 26 and through the several passageways defined by the pleatedshape. As the monopropellant decomposes, the products of. decompositionare directed into the open end of the heat exchanger to flowtherethrough and exit through the exhaust port 16. While the products ofdecomposition flow through the interior f the heat exchanger, thermalenergy is transferred through the walls of the heat exchanger and to theincoming fresh monopropellant, and as. in the other embodiments, theproducts of decomposition maintain an energy level condition within thereaction chamber which is capable of substaining decomposition of themonopropellant after the pyrotechnic igniter 20 has been deenergized orspent.

From the foregoing, it will be seen that a rocket engine or device forgenerating a jet of gases has been provided of simple construction,compact in size, having a minimum of parts, that is extremely eificient,and capable of starting and operating in a carbon free manner.

it will be understood that modifications and variations may be efifectedwithout departing from the scope of the novel concepts of the presentinvention, but it is understood that this application is to be limitedonly by the scope of the appended claims. 1

I claim as my invention:

1. A device for generating a jet of gases and sustaining decompositionof a fluid monopropellant such as used in a rocket engine comprising incombination a housing member having a wall defining -aclosed air-tightcylin-V drically shaped reaction chamber, a helically wound elongatedlength of tubular material positioned within said chamberconcentric'with the chamber and with the outer periphery of the coilspaced inwardly from the chamber walls to form an annular portion of thereaction chamber between the chamber wall and coil, the area within saidcoil forming a cylindrical portion of the reaction chamber, meansdefining an opening at one end of the coil communicating'with thereaction chamber, the inside of said tubular material of the coildefining an inner portion of the reaction chamber, means defining anexhaust port in said well of said housing member with the other end ofsaid coil connected to the wall to discharge through said exhaust port,orifice means located in said exhaust port to convert the pressure ofthe propellant gases through said coil and out of said port to kineticenergy, a first monopropellant fitting connected to the Wall of saidhousing and opening into said annular portion of the reaction chamber, asecond monopropellant fitting connected to the wall of said housing andopening into said cylindrical portion of said reaction chamber, apry-otechnic igniter having a pyrotechnic chamber with an open dischargeend, said igniter positioned with said open discharge end secured to andextending through the wall of said housing and opening'into saidreaction chamber outside of said coil adjacent the open end thereof sothat monopropellant fuel will be ignited in said annular portion andsaid cylindrical portion and will continue burning to said innerportion, the burning monopropellant gases flowing into said innerportion from both or" said annular and cylindrical portions, and anelectric igniter in said pyrotechnic chamber for igniting pyrotechnicignition material to ignite and cause decomposition of themonopropellant directed into the reaction chamber from said first andsecond monopropellant fittings.

2. A device for generating a jet of gases and sustaining decompositionof a fluid monopropellant such as used in a rocket engine comprising incombination a housing member having a wall defining a closed air-tightreaction chamber, a helically wound elongated coil of tubular materialpositioned within said chamber and dividing said reaction chamber into afirst outer portion outside of said tubular material of said coil andasecond inner portion within said tubular material of said coil, anopening in one end of the coil defined by-an angular cut across said oneend providing an elongated entry opening for decomposition products fromsaid first outer portion flowing to said second inner portion ofthereaction chamber, means defining an exhaust port in said Wall of saidhousing member with the other end of said coil connected to the wall todischarge through said exhaust port, orifice means located in saidexhaust port to convert the pressure of propellant gases flowing throughsaid coil and out of said port to kinetic energy, a monopropellantfitting connected to the wall of said housing and opening into saidreaciton chamber to direct monopropellant fuel into said outerportion ofsaid reaction chamber, a pyrotechnic igniter having a pyrotechnicchamber with an open end, said igniter positioned with said open endsecured to and extending through the wall of said housing and openingdirectly into said first outer portion of said reactionchamber outsideof said coil and adjacent said one open end of the coil to ignite themonopropellant in said first outer portion of the reaction chamber justbefore it flows into said second inner portion, and an electricaligniter in said pyrotechnic chamber for igniting pyrotechnic ignitionmaterial to direct a jet of burning pyrotechnic material into said outerportion of the reaction chamber to ignite and cause the decomposition ofmonopropellant directed into the first outer portion of the reactionchamber through the monopropellant fitting.

References Cited in the file of this patent UNITED STATES PATENTS

1. A DEVICE FOR GENERATING A JET OF GASES AND SUSTAINING DECOMPOSITIONOF A FLUID MONOPROPELLANT SUCH AS USED IN A ROCKET ENGINE COMPRISING INCOMBINATION A HOUSING MEMBER HAVING A WALL DEFINING A CLOSED AIR-TIGHTCYLINDRICALLY SHAPED REACTION CHAMBER, A HELICALLY WOUND ELONGATEDLENGTH OF TUBULAR MATERIAL POSITIONED WITHIN SAID CHAMBER CONCENTRICWITH THE CHAMBER AND WITH THE OUTER PERIPHERY OF THE COIL SPACEDINWARDLY FROM THE CHAMBER WALLS TO FORM AN ANNULAR PORTION OF THEREACTION CHAMBER BETWEEN THE CHAMBER WALL AND COIL, THE AREA WITHIN SAIDCOIL FORMING A CYLINDRICAL PORTION OF THE REACTION CHAMBER, MEANSDEFINING AN OPENING AT ONE END OF THE COIL COMMUNICATING WITH THEREACTION CHAMBER, THE INSIDE OF SAID TUBULAR MATERIAL OF THE COILDEFINING AN INNER PORTION OF THE REACTION CHAMBER, MEANS DEFINING ANEXHAUST PORT IN SAID WALL OF SAID HOUSING MEMBER WITH THE OTHER END OFSAID COIL CONNECTED TO THE WALL TO DISCHARGE THROUGH SAID EXHAUST PORT,ORIFICE MEANS LOCATED IN SAID EXHAUST PORT TO CONVERT THE PRESSURE OFTHE PROPELLANT GASES THROUGH SAID COIL AND OUT OF SAID PORT TO KINETICENERGY, A FIRST MONOPROPELLANT FITTING CONNECTED TO THE WALL OF SAIDHOUSING AND OPENING INTO SAID ANNULAR PORTION OF THE REACTION CHAMBER, ASECOND MONOPROPELLANT FITTING CONNECTED TO THE WALL OF SAID HOUSING ANDOPENING INTO SAID CYLINDRICAL PORTION OF SAID REACTION CHAMBER, APRYOTECHNIC IGNITER HAVING A PYROTECHNIC CHAMBER WITH AN OPEN DISCHARGEEND, SAID IGNITER POSITIONED WITH SAID OPEN DISCHARGE END SECURED TO ANDEXTENDING THROUGH THE WALL OF SAID HOUSING AND OPENING INTO SAIDREACTION CHAMBER OUTSIDE OF SAID COIL ADJACENT THE OPEN END THEREOF SOTHAT MONOPROPELLANT FUEL WILL BE IGNITED IN SAID ANNULAR PORTION ANDSAID CYLINDRICAL PORTION AND WILL CONTINUE BURNING TO SAID INNERPORTION, THE BURNING MONOPROPELLANT GASES FLOWING INTO SAID INNERPORTION FROM BOTH OF SAID ANNULAR AND CYLINDRICAL PORTIONS, AND ANELECTRIC IGNITER IN SAID PYROTECHNIC CHAMBER FOR IGNITING PYROTECHNICIGNITION MATERIAL TO IGNITE AND CAUSE DECOMPOSITION OF THEMONOPROPELLANT DIRECTED INTO THE REACTION CHAMBER FROM SAID FIRST ANDSECOND MONOPROPELLANT FITTINGS.